Biology subjects

Weroha, J.

Publications and source records attributed to Weroha, J..

4 recordsLinked to original sources

bioRxiv2026

Nuclear Cathepsin L Remodels the Replication Machinery to Create a Therapeutic Vulnerability in Ovarian Cancer

Abstract Therapeutic resistance in ovarian cancer is frequently driven by persistent replication stress, yet the molecular mechanisms that convert replication stress into a therapeutically exploitable vulnerability remain incompletely understood. Here, we identify drug-induced nuclear cathepsin L (nCTSL) as a previously unrecognized regulator of replication stress and DNA repair. Clofarabine (CLF) combined with the ATR inhibitor AZD6738, or the CHK1 inhibitor prexasertib promoted nuclear accumulation of CTSL, where it remodeled the replication machinery through degradation of CCNE1, MCM3, MCM6, and geminin, accompanied by loss of RAD51 and 53BP1 and increased {gamma}H2AX and phospho-RPA2. DNA fiber analysis demonstrated marked inhibition of replication fork progression following CLF-based combinations, whereas CTSL depletion accelerated fork progression and abolished therapy-induced replication stress. Reconstitution with the nuclear M1F CTSL isoform restored replication restraint, confirming a direct role for nuclear CTSL in regulating replication dynamics. GFP-based DNA repair reporter assays further revealed that CLF-based combinations suppress DNA repair competence in a CTSL-dependent manner, indicating that nuclear CTSL couples replication stress amplification with functional inhibition of repair pathways. Functionally, CLF-based combinations selectively targeted transformed fallopian tube secretory epithelial cells while sparing non-transformed counterparts, demonstrated broad activity in patient-derived ovarian cancer ascites spheroids, and significantly inhibited tumor growth and prolonged survival in vivo. Collectively, our findings identify nuclear CTSL as a mechanistic driver of replication stress that remodels the replication machinery, impairs DNA repair, and creates a therapeutically exploitable vulnerability in ovarian cancer. We propose that nuclear CTSL promotes a transition from replication competence to replication catastrophe, thereby establishing a conceptual framework for biomarker-guided therapeutic strategies targeting CTSL-dependent replication stress.

cancer biology↗

bioRxiv2025

Role of drug induced nuclear CTSL (nCTSL) in DNA damage response in cancer- therapeutic implications

ABSTRACT Background: Despite treatment advances, ovarian cancer (OC) remains the deadliest gynecological cancer, with a ~70% mortality rate. OCs initially respond to platinum chemotherapy but often develop resistance. While PARP inhibitors improve relapse-free survival in responsive cases, they do not extend overall survival. This underscores the need for effective combination therapies beyond BRCA status. The lysosomal protein cathepsin L (CTSL) can traffic to the nucleus, where it can regulate DNA repair and serve as a chromatin modifier. Here, we tested the hypothesis that nucleoside analog clofarabine (CLF) induced nuclear CTSL (nCTSL) serves as a biomarker of sensitivity to DNA-damaging agents in ovarian cancer. Methods: Role of nuclear CTSL in DNA damage, synergy with PARPis and CRM1 inhibitor, tumor regression was analyzed by 3D-spheroid culture, colony forming assay, subcellular fractions, comet assay, and IFC/ western-blotting using PARP inhibitor-sensitive and -resistant OC cell lines, ex vivo cultures of patient-derived OC ascites cells (OVA), primary OCs, and patient-derived xenografts (PDXs). Results: In OC cell lines, treatment with CLF induced nCTSL in a subset of models-designated CLF-responsive (CLF-r)-and sensitized them to the PARP inhibitors olaparib and rucaparib. In CLF-non-responsive (CLF-nr) models, nCTSL trafficking and drug synergy were achieved with the CLF+olaparib combination. Synergy was observed in 47% of CLF-r and 24% of CLF-nr OVA samples. Mechanistically, CLF monotherapy induced nuclear import of CTSL via KPNB1 in CLF-r cells, while combination treatment with CLF+olaparib was required in CLF-nr cells. CLF also downregulated the nuclear export protein CRM1 in both CLF-r and CLF-nr models. CTSL knockdown conferred resistance to CLF+olaparib in both cohorts, supporting a functional role for nCTSL in therapeutic response. Notably, in a subset of OVAs (29%) classified as CLF-resistant (CLF-Res), CLF failed to downregulate CRM1; however, pharmacological inhibition of CRM1 with KPT8602 restored sensitivity to CLF+PARP inhibitor treatment. In vivo, CLF+olaparib treatment in CLF-r and CLF-nr PDX models led to enhanced DNA damage, reduced tumor burden, and prolonged survival. Conclusion: Collectively, these findings identify nCTSL as a predictive marker of response to DNA-damaging therapies and support the CLF+olaparib combination as a promising strategy for overcoming drug resistance in OC via CTSL-mediated DNA damage.

cancer biology↗

bioRxiv2024

Functional impact of the hyperduplication genomophenotype in high copy number endometrial cancer

High copy number endometrial cancers (HCNEC) are dominated by excessive duplications scattered across the genome, termed here as the HyperDuplication GenomoPhenotype (HDGP). Although correlated with cancer progression, its biological significance and implications for therapy have not yet been established. We identified locations and sizes of duplications in 171 endometrial cancer cases and designated 71 HCNEC cases as HDGP. We also investigated the response to the pan-ERBB inhibitor afatinib in a subset of HDGP-EC cases with ERBB2/ERBB3 duplications using a patient-derived three-dimensional culture model. Our analysis demonstrates that beyond tandem duplications there is a more general pattern involving coordinated duplication of multiple distant regions of the genome, demonstrating preferential selectivity to over-expressed potential oncogenes within a broad network. This suggests that HDGP increases tumor fitness and resistance to therapy by perturbing important gene networks in concert rather than only driver genes, suggesting a mechanistic basis for the ineffectiveness of targeted drugs in these patients and highlighting the need for combination therapies in these highly aggressive cases.

genomics↗

bioRxiv2020

Acquired RAD51C promoter methylation loss causes PARP inhibitor resistance in high grade serous ovarian carcinoma

While loss of BRCA1 promoter methylation has been shown to cause PARP inhibitor (PARPi) resistance in high-grade serous ovarian carcinoma (HGSC), the impacts of RAD51C methylation (meRAD51C) remain unresolved. In this study, three PARPi-responsive HGSC patient-derived xenografts (PDX) with RAD51C gene silencing and homologous recombination deficiency were found to have either homogeneous or heterogeneous patterns of meRAD51C. PDX could lose meRAD51C following PARPi treatment (rucaparib/niraparib), where a single unmethylated RAD51C copy was sufficient to drive PARPi-resistance. Genomic profiling revealed this resistance was acquired independently in two distinct PDX lineages. Furthermore, we describe a patient sample where 1/3 RAD51C gene copies lost methylation following neoadjuvant chemotherapy. We show meRAD51C is a positive predictive biomarker for PARPi response and should be screened for routinely in patients. However, methylation loss in a single gene copy is sufficient to cause PARPi resistance and should be carefully assessed in previously treated patients considering PARPi therapy.

cancer biology↗